The present invention relates generally to new and useful devices and methods of packaging food products, and more specifically, to an improved tubular casing brake or sizing devices for food stuffing apparatus.
In the manufacture of sausage products, a tubular food casing, such as cellulose, is loaded onto the stuffing horn of a filling machine and stuffed with an emulsion, usually comprised of comminuted meat together with fillers, seasonings, spices, etc. In the case of small sausage products, like frankfurters, the filled casings are twisted, tied, or clipped into suitable links at predetermined intervals for further processing.
For larger diameter sausage products, like bolognas, salamis, and the like, the meat emulsion is introduced into larger, heavier walled fibrous type casings or casings formed from thermoplastic films, and formed into chubs or lengthy individual sticks. Like the smaller products, these large diameter sausage products are filled on stuffing machines comprising a meat pump and a delivery attachment in the form of a stuffing horn. However, unlike small diameter products, larger type sausage products, such as bologna, packaged in large code casings, rely on heavy-duty end-closures in the form of metal clips or caps which are frequently tied with a looped string, twine or other equivalent means, all for securely containing the meat emulsion during the stuffing process and for hanging or otherwise suspending the product during further processing, e.g., cooking and smoking, storage and display. U.S. Pat. No. 4,165,593 is one example of cut lengths of casing closed at one end with a clip for securing a loop for suspending the sausage product. The casing, with an end-closure clip and loop applied to one end, are manufactured in a first operation, and later, the opened end is fitted onto the horn of a filling machine, by a meat processor in an independent operation, where it is filled and then closed at the second end.
In stuffing both small and large diameter casings a sizing or braking system can be employed for controlling casing expansion to avoid exceeding casing manufacturers recommended stuffing diameters while also preventing back "purge" of meat emulsion. This is achieved with a brake device which applies uniform pressure to the exterior wall of unfilled casing on a stuffing horn as emulsion fills the casing interior. The braking device, which may comprise a ring assembly, engages the casing, restricting its rate of withdrawal from the horn by applying pressure or drag, generated by friction, to the casing as it is pulled from the horn by the meat emulsion being filled or stuffed into that casing. Representative brake systems are disclosed by U.S. Pat. Nos. 3,748,690 (Niedecker); 3,621,513 (Kupcikevicius); 3,457,588 (Myles et al); 4,438,545 (Kupcikevicius et al) and 4,558,488 (Martinek), to name but a few.
In most brake/sizing systems compressive force is applied uniformly and circumferentially (360.degree.) to the outer casing wall forcing it against the stuffing horn, thus creating friction between the inner casing wall and the stuffing horn and, respectively, between the outer casing wall and the brake/sizing system. The stuffing cycle typically begins with the operator loading a precut length of casing onto the stuffing horn with the first end of the casing having an end-closure, e.g. it may be tied or clipped, and it may have a looped string attached to the end-closure. The closed, first end of the casing is brought flush with the outlet end of the horn. The horn and the brake ring opening are, next, axially aligned. The brake ring assembly is then forced over the outer wall of the casing, which is on the horn, so that compressive force is applied to the casing, pushing it against the horn at a point adjacent to the outlet end of the horn. Frequently, however, in the process the looped string hanging from the clipped or capped end-closure or string tied casing becomes "locked" between the brake ring and casing side wall. Consequently, unless the string is released before stuffing is initiated, the casing is unable to peel off the horn and pressure builds up quickly at the outlet end of the horn causing the casing to rupture. This means costly down time for cleanup, lost meat emulsion, lost production and wasted casings.
Accordingly, the present invention contemplates improved sizing/braking devices for food stuffing apparatus for filling casings, string tied/looped or otherwise, which can significantly reduce snagging of the string, where used, and consequent casing rupture. This translates into economic advantage through higher production efficiency with reduced potential for down time.
A further important consideration in preparation of both large and small diameter sausage products is the maintenance of accurate diametrical and circumferential size control over the entire length of the sausage stick. It is particularly important that the diameter of the large sausage products be carefully controlled so that meat packers are able to cut the sausage into slices of predetermined thickness and diameter for prepackaging. The objective is to have a given number of slices weigh precisely a predetermined amount for each package. For the smaller products, it is critical that uniform diameters be maintained so that, for example, when the sausage product is formed into links, each link weighs the same as all other links, thus enabling the packaging of those links into standard weight containers. As a result, meat processors are constantly striving to improve operations that affect finished package yields. Constant sizing control of green stick diameter, during stuffing, assures more uniform slice and/or link weight and minimizes the over and under weight variations of the packages.
U.S. Pat. Nos. 3,748,690 and 3,872,543 to Niedecker disclose popular style sizing devices for controlling product diameter. During filling, controlled release of casing is achieved by a snubbing element bearing against the outlet end of the stuffing horn with the casing therebetween. It has been found, however, that the outlet end of stuffing horns can be fragile and subject to bending and loss of cylindrical shape unless specially reinforced. Because of distortion in roundness of horn outlets, snubbing rings, particularly those which operate by engaging the edge of stuffing horns, such as disclosed by the Niedecker patents, can fail to provide accurate product diameter control during filling operations.
Although snubbing lips of devices like those of Niedecker are fabricated from essentially resilient materials, they are nevertheless made relatively rigid and nonflexible due to steel backing members exerting pressure thereon. Consequently, desired flexibility and resiliency of such devices may be lost, to a significant degree, at the point of constriction of casing against the filling horn, making it difficult for irregular shaped folds in casing to smoothly negotiate constriction points without producing deviations in constant pressures and, ultimately, variations in product diameter. Rigid steel holders for such devices also shorten the useful life expectancy of their sizing rings due to excess wear.
Accordingly, the present invention contemplates inter alia improved flexibility and longer wearing sizing devices which offer a high degree of dimensional uniformity and caliber control without dependence on horn roundness and cylindrical shape for optimum size control during stuffing, and without casing wall thickness variations interfering with sizing ring performance.